The relationship between residual insulin secretion and metabolic stability in type 1 (insulin dependent) diabetes

The purpose of this study was to investigate whether the great differences in metabolic control between labile and stable insulin dependent juvenile diabetics could be explained by differences in residual pancreatic B cell function. Nine labile diabetics, ten stable diabetics on one insulin injection a day and nine stable diabetics on two insulin injections a day were investigated during a 24-h period during which they maintained their usual diet and insulin therapy. Serum C-peptide concentrations were measured after removal of proinsulin bound to insulin antibodies. The labile diabetics did not show any significant change in C-peptide concentrations despite great fluctuations in plasma glucose concentrations. In six patients with stable diabetes, C-peptide responses after the main meals could be demonstrated and there was a significant correlation between the concentrations of C-peptide and glucose (r = 0.85, p less than 0.001). The other stable patients, having the same mean plasma glucose concentration and mean amplitude of glycaemic excursions, did not show any C-peptide response. It is concluded that persistent insulin secretion is not a prerequisite for metabolic stability. Severe lability, however, seems to occur only in the absence of residual insulin secretion.